Description

Out-of-bounds read in Microsoft Office Excel allows an unauthorized attacker to disclose information over a network.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "6.5",
  "pubDate": "2026-08-11T17:19:10.513Z",
  "pubdate": "2026-08-11T17:19:10.513Z",
  "executiveSummary": "This vulnerability is classified as an out-of-bounds read security defect affecting Microsoft Office Excel.\nThe primary impact of this flaw is unauthorized information disclosure across a network vector, potentially exposing sensitive memory contents or local system data to an adversary.\nThe affected systems comprise instances of Microsoft Office Excel processing maliciously crafted spreadsheet files.\nThe risk implications include the potential leakage of confidential information stored within process memory or adjacent data structures, which could facilitate subsequent, more advanced exploitation phases such as bypasses of memory randomization mechanisms.\nAn unauthorized remote attacker is capable of initiating the attack sequence by enticing a victim to open a specially crafted file or interacting with a vulnerable parsing routine.\nExploitation requirements generally involve user interaction, specifically the opening of a malicious document within the context of the affected software.\nThe vulnerability underscores the inherent risks associated with complex file format parsers failing to adequately validate boundary conditions during memory read operations.",
  "technicalDetails": "The root cause of the vulnerability stems from an out-of-bounds read condition residing within the memory management and parsing logic of Microsoft Office Excel.\nSpecifically, when processing specially crafted input files, the application fails to adequately verify the boundaries of allocated buffer structures or input length parameters prior to executing read operations.\nThe vulnerable component involves the internal file parsing engine responsible for interpreting structured document formats within Microsoft Office Excel.\nThe exploitation method relies on supplying malformed structural metadata or offset values within a target file that misleads the parsing routine into reading data outside the intended memory boundaries.\nThe attack flow proceeds as follows: first, the unauthorized attacker crafts a malicious spreadsheet file containing manipulated header values or structural records designed to trigger the out-of-bounds index calculation.\nSecond, the attacker delivers this file to the target user via network-based vectors such as email attachments or shared storage repositories.\nThird, the victim opens the malicious file using a vulnerable version of Microsoft Office Excel.\nFourth, during the parsing phase, the application attempts to read data from an invalid memory address dictated by the manipulated input values.\nFifth, the out-of-bounds read operation accesses adjacent memory regions, potentially capturing sensitive data residing on the heap or stack.\nFinally, depending on the implementation and subsequent data handling, the disclosed information may be exfiltrated or leveraged by the attacker over the network if coupled with secondary vulnerabilities or interactive feedback channels.\nAuthentication requirements are absent, as the file can be processed independently upon user interaction.\nPrivilege requirements are minimal, executing within the standard security context of the user running the application.\nNetwork exposure is inherent to the delivery mechanism of the crafted file and subsequent unauthorized information disclosure over a network.\nPayload behavior centers on memory inspection and unintended data retrieval rather than direct code execution or privilege escalation."
}